Never-before-seen video of the Challenger space shuttle disaster has surfaced after almost a quarter-century locked away in a Florida basement.

The chilling amateur footage was recorded by retired optometrist Jack Moss on his new home video camera on the morning of 28 January 1986.

The four-minute film captures the moment the shuttle exploded, 73 seconds after launch from Florida's Kennedy Space Centre, killing all seven astronauts on board and setting Nasa's manned spaceflight programme back years.

It is believed to be the only amateur film in existence of the world's worst space disaster, recorded in an era before mobile phone cameras, when even home camcorders were rare.

"I don't think Mr Moss thought it was anything significant. He put it down in his basement with other tapes he had and just forgot about it," said Marc Wessels, executive director of the Space Exploration Archive, a Kentucky-based group that collects space memorabilia for educational purposes.

"It's a unique vignette of a moment in history. We've seen the pictures from the ground at the point of explosion at Cape Canaveral, but never anything like this. It's remarkable raw footage."

The tape surfaced after Moss told Wessels last year that he had watched the launch from the front yard of his house in Winter Haven, Florida, about 80 miles from Cape Canaveral.

"I said we needed to talk about it and he just said casually, 'Yeah, I even have it on video'," said Wessels, who was also Moss's pastor before he died from cancer in December.

"He said I could have the tape when he died. It took a while to find someone with an old Betamax video player, then I had to watch four hours of gameshows and sitcoms from the 1980s, but when I found the Challenger film my reaction was that people really have to see this."